System and method for reducing the placebo effect in controlled clinical trials

ABSTRACT

A method and system for performing a clinical trial having a reduced placebo effect is disclosed. The method includes randomizing study participants into three or more treatment groups and performing a first phase of testing on the groups. In a typical embodiment, the first phase of testing includes administering an active treatment to a first group, and administering a placebo to a second group and to a third group. Responders and non-responders are determined for each group. A second phase of testing is then performed. The second phase of testing includes administering the placebo to non-responders in the first group, administering the active treatment to non-responders in the second group, and administering the placebo to non-responders in the third group. The data from the first phase of testing and from the second phase of testing is pooled and analyzed to determine response rates to active treatment and placebo.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 12/545,562 filed on Aug. 21, 2009; which is acontinuation of patent application Ser. No. 10/814,852 filed on Mar. 31,2004, which claims the benefit of provisional patent application No.60/459,517 filed Mar. 31, 2003; which applications are herebyincorporated herein by reference in the entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable

FIELD OF THE INVENTION

The present invention relates generally to clinical trials and morespecifically to a method and apparatus for reducing the placebo effectand sample size requirements in such clinical trials.

BACKGROUND OF THE INVENTION

As is known in the medical field, the term “clinical drug treatmentstudy” or “clinical drug trial” (or more simply a “clinical trial”),refers to the testing done on humans to determine the value of a givendrug treatment. A clinical drug trial is referred to as a “controlleddrug trial” when the effect of a drug treatment is measured against acomparison treatment or treatments administered over the same timeperiod and under similar conditions. In the most typical form ofcontrolled clinical trial, the comparison treatment is provided bysupplying a placebo to test study participants in place of the actualtreatment (placebo-controlled clinical trial).

As is also known, the term “blinding” in a clinical drug trial refers tothe concealment of treatment assignment in order to prevent influencingthe behavior, observation or reporting of the person receiving thetreatments or of the person administering the treatment. In a doubleblind, clinical drug trial, both the persons receiving the treatment andthe persons administering the treatment are unaware of which studyparticipants are receiving which treatments.

As is also known, the term “randomization” in a clinical drug trialrefers to the random assignment to treatment, so that a random sequencedetermines whether a given subject is assigned to active treatment(s) orplacebo. Randomization is an important aspect of a clinical trial inthat it eliminates possible biases in treatment assignment.

The purpose of a randomized, double-blind, placebo-controlled trial isto compare the efficacy of a specific treatment or treatments with thatof placebo for study participants identified according to a prioricriteria and assigned by chance to a given treatment group. Theconventional design of such a trial involves the parallel comparison ofone or more treatments with placebo, with sample sizes consideredadequate to detect a therapeutic signal, given the expected placeboresponse rates in that specific population. As the term is commonlyused, “placebo response” represents an apparent improvement in theclinical condition of study participants randomly assigned to theplacebo treatment, (e.g., a pre-post treatment change within the placebogroup). It is not uncommon for clinical trials to yield uninterpretableresults, due in part to the placebo response. It has been suggested thataddressing the placebo response issue is one of the most importantchallenges facing the future of industry-sponsored psychopharmacologicdrug development.

SUMMARY OF THE INVENTION

In accordance with the present invention, a method of performing aclinical trial having a reduced placebo effect is disclosed. In onetypical form, the method includes randomizing study participants intothree treatment groups and performing a first phase of testing on thethree groups. The first phase of testing comprises administering anactive treatment to a first group, and administering a placebo to asecond group and to a third group. Responders (i.e. those studyparticipants who respond to either a treatment or a placebo) andnon-responders (i.e. those study participants who do not respond toeither a treatment or a placebo) are determined for each group. A secondphase of testing is then performed. The second phase of testingcomprises administering the placebo (or continuing the active treatment)to non-responders in the first group, administering the active treatmentto non-responders to placebo in the second group, and continuing toadminister the placebo to non-responders in the third group. The datafrom the first phase of testing and from the second phase of testing areanalyzed to estimate the response rates to active treatment and toplacebo. Since non-responders to placebo treatment in the first phaseare used in the second phase, their placebo response in the second phaseis likely to be reduced.

A system for performing a clinical trial having a reduced placebo effectis also presented. The system includes means for establishing a pool ofeligible study participants, means for establishing a pool of enrolledand randomized study participants, means for identifying a pool of studyparticipants completing a first phase of the study, means foridentifying a pool of study participants for use in a second phase ofthe study, means for identifying a pool of study participants completingthe second phase of the study, and means for generating data based oneach phase of the study and means for analyzing the data. The first poolof enrolled and randomized study participants is used to enroll andrandomize eligible study participants who agree to be randomized intoone of three groups: a treatment group/arm, a first placebo group/armand a second placebo group/arm. The first phase of the study administersactive treatment to the first group/arm and placebo to the second andthird groups/arms. After completion of the first phase of the study, thegroups are separated into responders and non-responders. Thenon-responders to active treatment enter a second phase of the studywhere they are typically administered placebo or continue activetreatment (to maintain the blinding during the second phase of thestudy). The non-responders to placebo during the first phase of thestudy will receive active treatment during the second phase of the study(in the case of second group/arm) or will continue to receive placeboduring the second phase of the study (in the case of the thirdgroup/arm). Alternatively, patients may be randomized to drug or placeboduring the first phase, and non-responders to placebo during the firstphase are re-randomized to drug or placebo during the second phase. Theresultant data from the first phase of the study and the second phase ofthe study are processed through a set of data analysis in order todetermine the overall effectiveness of the active treatment(s) comparedto placebo.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features of this invention, as well as the inventionitself, may be more fully understood from the following description ofthe drawings in which:

FIG. 1A is a block diagram of a system for designing and/or implementinga study having reduced placebo effect;

FIG. 1B is a block diagram of an embodiment of a system for designingand/or implementing a study using the techniques of the presentinvention;

FIG. 2 is a flow diagram which describes a process to design and/orperform a clinical trial having a reduced placebo effect;

FIG. 3 is a block diagram of a first study example; and

FIG. 4 is a block diagram of a second study example.

DETAILED DESCRIPTION OF THE INVENTION

Before turning to the figures, it may first be helpful to provide ageneral overview and define some terminology. The present inventioncomprises a system and technique for implementing a study and a relatedanalytical plan aimed at reducing both an overall placebo response rateand a sample size requirement for clinical trials. By reducing theplacebo response rate and the sample size, the present invention can,among other things, lower the expense and time required to evaluate theefficacy of new therapeutic compounds.

The technique of the present invention utilizes two phases of treatment.The first phase involves a so-called “unbalanced randomization” betweena placebo treatment group/arm and one or more active treatment(s)group(s)/arm(s). In such an unbalanced randomization, a greater numberof study participants are randomly placed in a treatment group/arm wherethey will receive a placebo treatment rather than an active treatment.Thus, more study participants are said to be “randomized to placebo”than are “randomized to active treatment(s)” hence the term“unbalanced.”

At the end of the first phase, so-called “responders” (i.e. those studyparticipants who are given the active treatment and who respond to theactive treatment as well as those study participants who are given theplacebo and respond to the placebo) and non-responders (i.e. those studyparticipants who are given the active treatment and who do not respondto the treatment as well as those study participants who are given theplacebo and who do not respond to the placebo) are identified. For thepurpose of the related analytical plan, only the data from the firstphase of the study will be considered for the responders. However,responders to active treatment in the first phase may go on to continuethe assigned double-blind treatment or may go on to open continuationtreatment or may simply stop treatment.

In the second phase, non-responders treated with placebo in the firstphase are randomized to either active treatment (or treatments) orplacebo. Since study participants in the second phase have already notresponded to a placebo treatment during the first phase, the number ofresponders to placebo treatment in the second phase will besubstantially reduced. That is, on a percentage basis, fewer studyparticipants will respond to the placebo in the second phase thanresponded in the first phase. The detailed study design, referred to asSequential Parallel Comparison Design (SPCD) is represented by the blockdiagrams of FIGS. 1A and 1B and the flow diagram of FIG. 2. Theanalytical plan of the SPCD pools the data from both phases (with allthe randomized study participants from the first phase and with allplacebo non-responders during the first phase in the second phase) toincrease the effectiveness of the analysis and reduce the requiredsample size.

Referring now to FIG. 1A, a block diagram of a system 1 implementing aclinical drug study (or trial) utilizing the techniques of the presentinvention includes a pool of study participants 10 who are eligible toparticipate in the clinical trial. The pool of eligible studyparticipants 10 may include subjects who are deemed to be appropriatefor the study (based on clinical and sociodemographic characteristics)and may possibly participate in the study. As is generally known, suchpossible study participant characteristics of interest are thosecharacteristics which are relevant or important to the clinical trialbeing designed. It should be appreciated that those of ordinary skill inthe art of clinical trial design will know how to select suchcharacteristics. Information relevant to the study as well asinformation on the pool of eligible study participants may be stored ina storage device such as a database, for example.

A study participants selection processor 11, coupled to the pool ofeligible study participants 10 analyzes study participantcharacteristics and determines their appropriateness for inclusion in aparticular clinical trial. Once selected, the pool of enrolled andrandomized study participants 12 will include eligible studyparticipants (e.g., having characteristics meeting certain prespecifiedcriteria) who are identified and selected to participate in the clinicaltrial, who agree to participate in the study and be randomized as partof the study. It should be appreciated that the analysis performed toidentify and select study participants may be done by a person with orwithout the aid of a processor such as a subject selection processor.

Once the study participants in the clinical drug trial are enrolled, theenrolled study participants are randomly placed into two groups. Onegroup will receive active treatment and is designated T₁. The remaininggroup will receive placebo and is designated as P₁.

A first phase of the study 14 is then conducted on both groups. Theduration of the first phase of the study will vary according to thecondition under investigation and must allow enough time for the activetreatment to show a difference compared with the placebo. The pool ofstudy participants completing the first phase of study 14 are arrangedinto four groups. A first group is designated RT₁ and comprises studyparticipants who showed a response to active treatment. A second groupis designated RP₁ and comprises study participants who showed a responseto placebo. Both the RT₁ group and the RP₁ group are excluded from theanalytical aspect of the second phase of the study, although they maycontinue treatment as an extension of the double-blind treatmentassignment or through an open treatment. A third group is designatedNRT₁ and comprises study participants who did not show a response(non-responders) to active treatment. This group is included in thesecond phase of the study, although the data collected during the secondphase of the study are not included in the analyses. The NRT₁ group maycontinue to receive active treatment during the second phase of thestudy or may go on placebo during the second phase of the study (inorder to maintain the blinding). A fourth group, designated NRP₁,comprises study participants who did not show a response to placebo.

The NRP₁ group is provided to the pool of study participants into asecond phase of the study 16. A randomization process is performed onthis group 16 in order to randomly assign members of the NRP₁ group intoa first treatment group/arm called T₂ where they will receive activetreatment during the second phase of the study, and a second group/armdesignated as P₂ where they will receive placebo during the second phaseof the study.

The pool of study participants completing the second phase of study 18results from the second phase of the study which is similar to the firstphase of the study, and will typically include the same treatment(s) andplacebo and have the same duration.

The pool of study participants completing the second phase of the study18 are arranged into four groups. A first group, designated RT₂,comprises study participants who showed a response to active treatment.A second group, designated NRT₂, comprises study participants who didnot show a response to active treatment. A third group, designated RP₂,comprises study participants who showed a response to placebo. A fourthgroup, designated NRP₂ comprises study participants who did not show aresponse to placebo.

The data are then analyzed through a set of data analysis 20 to provideclinical trial results. This may, for example, be accomplished in a dataanalyzer. The analysis 20 utilizes data from the RP₁, RT₁, NRP₁, NRT₁,NRP₂, RP₂, NRT₂ and RT₂ groups. Thus data from both the first and secondphases of the study are analyzed to provide the clinical trial results.

It should be appreciated that in some embodiments or applications, itmay be desirable to use more than two study phases and to arrange theparticipants into more than four discrete groups.

Referring now to FIG. 1B, a block diagram of a second system 1′implementing a clinical drug study utilizing the techniques of thepresent invention includes a pool of study participants 10 who areeligible to participate in the clinical trial. The pool of eligiblestudy participants 10 may include subjects who are deemed to beappropriate for the study (based on clinical and socio-demographiccharacteristics) and may possibly participate in the study. As isgenerally known, such possible study participant characteristics ofinterest are those characteristics which are relevant or important tothe clinical trial being designed. It should be appreciated that thoseof ordinary skill in the art of clinical trial design will know how toselect such characteristics.

A study participants selection processor 11, coupled with the pool ofeligible study participants 10 analyzes study participantcharacteristics and determines their appropriateness for inclusion. Onceselected, the pool of enrolled and randomized study participants 12′will include eligible study participants (e.g., having characteristicsmeeting certain prespecified criteria) who are identified and selectedto participate in the clinical trial, who agree to participate in thestudy and be randomized as part of the study. It should be appreciatedthat the analysis performed to identify and select study participantsmay be done by a person with or without the aid of a processor such as asubject selection processor.

Once the study participants in the clinical drug trial are enrolled, theenrolled study participants are randomly placed into three groups. Onegroup will receive active treatment and is designated T₁. The remainingtwo groups will receive placebo and are designated together as P₁ andP₂.

A first phase of the study is then conducted on all three groups. Theduration of the first phase of the study will vary according to thecondition under investigation and must allow enough time for the activetreatment to show a difference against placebo. The pool of studyparticipants completing the first phase of study 14′ are arranged intosix groups. A first group is designated RT₁ and comprises studyparticipants who showed a response to active treatment. A second groupis designated RP₁ and comprises study participants who showed a responseto the first placebo group/arm. A third group is designated RP₂ andcomprises study participants who showed a response to the second placebogroup/arm (typically the same as the first placebo). The RT₁ group, RP₁group and the RP₂ group are excluded from the analytical aspect of thesecond phase of the study, although they may continue treatment as anextension of the double-blind treatment assignment or through an opentreatment. A fourth group is designated NRT₁ and comprises studyparticipants who did not show a response (non-responders) to activetreatment. A fifth group, designated NRP₁, comprises study participantswho did not show a response to the first placebo group/arm. A sixthgroup, designated NRP₂, comprises study participants who did not show aresponse to the second placebo group/arm.

The NRT₁ group, NRP₁ group and NRP₂ group are used to form the pool ofstudy participants completing a second phase of study 18 which resultsfrom the second phase of the study which is similar to the first phaseof the study, and will typically include the same treatment and placeboand have the same duration. The NRP₁ group will receive active treatmentduring the second phase of the study, the NRP₂ group will continue toreceive placebo during the second phase of the study. The NRT₁ group maycontinue to receive active treatment during the second phase of thestudy or may go on placebo during the second phase of the study (inorder to maintain the blinding), although the data collected during thesecond phase of the study are not included in the analyses.

The pool of study participants who complete the second phase of thestudy are arranged into six groups. A first group, designated R-NRP₂,corresponds to those study participants who did not respond to placeboin the first phase of the study but showed a response to placebo in thesecond phase of the study. A second group, designated NR-NRP₂,corresponds to those study participants who did not respond to placeboin the first phase of the study and did not show a response to placeboin the second phase of the study as well. A third group, designatedR-NRP₁, corresponds to those study participants who did not respond toplacebo in the first phase of the study but showed a response to activetreatment in the second phase of the study. A fourth group, designatedNR-NRP₁, corresponds to those study participants who did not respond toplacebo in the first phase of the study and who did not show a responseto active treatment in the second phase of the study. A fifth group,designated R-NRT₁, corresponds to those study participants who did notrespond to active treatment in the first phase of the study but showed aresponse to active treatment (or placebo) in the second phase of thestudy. A sixth group, designated NR-NRT₁, corresponds to those studyparticipants who did not respond to active treatment in the first phaseof the study and did not show a response to active treatment (orplacebo) in the second phase of the study.

The data are then analyzed using a set of data analysis tools 20′. Theanalysis 20′ utilizes data from the RP₁, RT₁, RP₂, NRP₁, NRT₁, NRP₂,R-NRP₂, NR-NRP₂, R-NRP₁, and NR-NRP₁, groups. Thus data from both phasesof the study are analyzed to provide the clinical drug trial results andto compare the effects of the active treatment(s) and placebo.

A flow diagram of the presently disclosed method is depicted in FIG. 2.The rectangular shaped elements are herein denoted “processing blocks”and the diamond shaped elements, are herein denoted “decision blocks.”It should be appreciated that all, some or none of the functionsprovided in each of the processing and decision blocks may be carriedout by humans or may be carried out by processors. Thus in oneembodiment, the “processing blocks” represent computer softwareinstructions or groups of instructions and the “decision blocks”represent computer software instructions, or groups of instructionswhich affect the execution of the computer software instructionsrepresented by the processing blocks. It should be noted that the flowdiagram of FIG. 2 represents one embodiment of the design and variationsin such a flow diagram which generally follow the process outlined aboveand are considered to be within the scope of the present invention.

Alternatively, the processing and decision blocks represent processeswhich can be performed by functionally equivalent circuits such as adigital signal processor circuit or an application specific integratedcircuit (ASIC). The flow diagrams do not depict the syntax of anyparticular programming language. Rather, the flow diagrams illustratethe functional information one of ordinary skill in the medical fieldrequires to perform the functions/processes in accordance with thepresent invention. It should be noted that many routine programelements, such as initialization of loops and variables and the use oftemporary variables are not shown. It will be appreciated by those ofordinary skill in the medical field that unless otherwise indicatedherein, the particular sequence of steps described is illustrative onlyand can be varied without departing from the spirit of the invention.Thus, unless otherwise stated the processes described below areunordered meaning that, when possible, the processes can be performed inany convenient or desirable order.

Referring now to FIG. 2, a flow diagram showing the SPCD methodology 30for performing a clinical trial is shown. Before describing the steps indetail, it should be appreciated that a clinical trial designed and/orimplemented in accordance with the present invention is conducted in atleast two phases and the phases can be of equal duration. While in someclinical trials it is preferable to have the duration of each phase bethe same, it should be appreciated that in the present technique, eachphase may have a different duration. It should also be appreciated thatin some clinical trials, the duration of each phase is shorter than thatof standard clinical trials and capitalizes on the observation thatdrug-placebo differences can be detected relatively early in theclinical trial. There may, however, be some instances when the durationof each phase is the same as or even larger than that of standardclinical trials. The particular duration of each phase of the clinicaltrial is selected in accordance with a variety of factors including (butnot limited to) the type of disorder under investigation, the naturalcourse of the disorder, the estimated placebo response rate, and theestimated proportion of study participants continuing into the second(or later) phase of the study.

It should be appreciated that in some cases a trade-off must be madebetween lowering the placebo response rate and exposing the studyparticipants to the treatment. For example, a drug company may want asmany people as possible to be exposed to a particular active drugtreatment. The design will reflect such considerations.

Turning now to FIG. 2, processing begins in processing block 32 inwhich, after an initial screening visit, eligible study participants arerandomly allocated to one of three possible treatment groups: drug alone(DP), placebo then drug (PD) and placebo then placebo (PP). Theallocation is done in an unbalanced ratio. One possibility is using a2:3:3 ratio (DP:PD:PP) in blocks of 8 to maintain the 2:3:3 ratiobetween groups. However, in general, the ratio could be 1-2a,a,a for achoice of “a” (in units of percent %) to maximize power (see examplesdiscussed below in conjunction with FIGS. 3 and 4).

It should be appreciated that in a preferred embodiment, the same numberof study participants are included in the placebo-drug (PD) and theplacebo-placebo (PP) treatment groups. If a 2:3:3 ratio is used duringthe first phase of the trial, 75% (or 2a) of the study participants arerandomized to placebo and 25% (or 1-2a) are randomized to activetreatment. The specific ratio used can be of any values, with severalfactors leading to selection of a particular ratio. A ratio whichresults in potential study participants having a relatively high overallchance (e.g., 50%) for assignment to active treatment is typicallypreferred by study participants. The 2:3:3 ratio yields approximately a50% chance of a study participant being assigned to active treatment. Ingeneral, however, any ratio which results in more non-responders toplacebo for phase two of the study is more informative as data comesfrom phase two of the study as well.

Processing block 34 recites that the first phase of the study isperformed. This includes administering the active treatment to the DPgroup and administering placebo to the PD group and to the PP group.

Processing block 36 discloses that at the end of the first phase of thestudy, a study clinician or administrator determines whether eachparticipant is a responder or a non-responder. That is, responders andnon-responders for the DP group, responders and non-responders for thePD group, and responders and non-responders for the PP group aredetermined.

Processing block 38 recites that the responders for each of the groupsexit the double-blind study (from a data analysis perspective). Theseresponders can continue double-blind treatment, enter an open-labelcontinuation therapy, follow-up, or simply discontinue theirdouble-blind treatment. Non-responders for each group at the end of thefirst phase of the study participate in a second phase of similarduration. It should be appreciated that in the second phase of thestudy, the placebo will be administered in a double-blind fashion.

Next, as shown in processing block 40, those study participants in thefirst phase who were non-responders to the active treatment receiveplacebo (or may continue to receive active treatment) in the secondphase of the study (so that we do not unblind study participants andinvestigators).

Next as shown in processing block 42, those study participants in thefirst phase who were part of the first group/arm to receive placebo andwho were non-responders to the first placebo receive active treatment inthe second phase of the treatment will be administered in a double-blindfashion as part of the second phase of the study.

In processing block 44, those study participants in the first phase whowere part of the second group/arm to receive placebo and who werenon-responders to the placebo receive placebo again in the second phaseof the study. Similar to the other groups in the second phase of thestudy, the placebo will be administered in a double-blind fashion.

The second phase of the study begins in processing block 46. Since thosestudy participants in the second phase have already failed to respond toplacebo in the first phase (i.e. they have already “failed placebo,”)their placebo response will be reduced.

As shown in processing block 48, at the end of the second phase of thestudy, the study clinician or administrator determines whether eachparticipant is a responder or a non-responder. That is, responders andnon-responders in each of the three groups, are determined.

As shown in processing block 50, the data from both phases are pooledand analyzed. By pooling the data, it is possible to maximize power andreduce the required sample size. The response rates of the first phaseof testing are pooled with the response rates of the second phase (forthe placebo non-responders during the first phase only), therefore theresponse of each patient is counted twice, which results in a smallersample size being required to achieve a requisite power for the study.Processing then ends as shown in processing block 51.

In one embodiment, the effect of the active treatment is assessed usinga z-score, which has a normal distribution with a standard deviationof 1. The z-score is computed by pooling the data from all threetreatment groups and using a pooling ratio to maximize power. Under thenull hypothesis of no drug placebo difference, the z-score will have amean value of zero. In this way, all the data from the first and secondphases of the study is used in the analysis allowing for a smallersample size (i.e. higher power). It should be noted that data from thestudy participants who failed active treatment in the first phase of thestudy (DP group) and who are exposed to placebo during the second phaseof the study is not used to calculate the placebo response rate.Similarly, in the event that subjects that fail active treatment in thefirst phase are kept on active treatment during the second phase, theirresponses are not counted as part of the analysis.

While the present description involves the comparison of one activetreatment and placebo without an active comparator, it should beunderstood that a version of this design could be developed for trialswith multiple active comparators.

Referring now to FIG. 3, a diagrammatic representation illustrates thephases and organization of a planned smoking cessation study arrived atusing the above-described methodology to design a clinical study.

As shown in FIG. 3, a group of subject smokers 110 a are divided intothree possible groupings as follows: (1) those who are excluded from thestudy 120 a; (2) those who are eligible to participate in the study andwho agree to be randomized 122 a; and (3) those who are eligible toparticipate in the study but who decline to be randomized 124 a. Theeligible study participants who agree to be randomized (i.e. group 122a) are randomized into three groups identified as 130 a, 132 a, and 134a in FIG. 3. This selection process is referred to as the subjectselection phase.

Next, in phase one of the study, a first group 130 a receives activetreatment. In this particular example, where the eligible studyparticipants are smokers, they receive the active treatment for fourweeks. The particular length of time of any study depends upon a varietyof factors well known to those of ordinary skill in the medical field.

A second group 132 a receives placebo for the same duration of time inwhich group 130 a which receives the active treatment (i.e. studyparticipants in group 130 a receive the active treatment for 4 weeks andstudy participants in group 132 a receive the placebo treatment for 4weeks).

Similar to the second group, a third group 134 a also receives placebofor the same duration of time as the first group 130 a and the secondgroup 132 a.

Once the first phase of treatment has been completed, the studyparticipants in each of the groups 130 a, 132 a, 134 a are separatedinto responders and non-responders. In group 130 a, those studyparticipants who quit smoking are considered responders (specifically,responders to treatment) and those study participants who do not quitsmoking are considered non-responders (specifically, non-responders totreatment). Similarly, in groups 132 a, 134 a, those study participantswho quit smoking are identified as responders (specifically, respondersto placebo) while those study participants who do not quit smoking areidentified as non-responders (specifically, non-responders to placebo).

After the responders and non-responders are identified, phase two of thestudy begins. For the active treatment group 130 a, responders 140 adiscontinue further treatment. Non-responders 142 a, on the other hand,continue the study and receive placebo for the duration of phase two(which, in this particular example, is another four week phase).

The first placebo group responders 144 a discontinue further treatment,while the first placebo group non-responders 146 a continue the studyand receive active treatment for the duration of phase two of the study.

The second placebo group responders 148 a discontinue further treatment,while the second placebo group non-responders 150 a continue the studyand receive placebo for the duration of phase two of the study. In analternate embodiment the first and second placebo group non-respondersare grouped together during phase 1 and then randomized into a groupthat will receive active treatment and a group that will receive placeboduring the second phase of the study.

After the second phase is completed, the data from both the first andsecond phases of the study are analyzed to determine the effectivenessof the active treatment(s) compared to placebo. One exemplary analysisis described next. While a preferred method of performing the analysisis described below, it should be appreciated that other methods ofperforming analysis of the data are also within the scope of the presentinvention.

In the below analysis of the data from the smoking cessation study, itis assumed that study participants will have an initial response rate of45% on drug and 25% on placebo. It is further assumed that thenon-responders to placebo will have a response rate of 25% on drug and10% on placebo. These assumptions are based on prior studies in thefield of smoking cessation research.

Using the SPCD methodology, 172 study participants would be needed toachieve 90% power based on the well-known asymptotic formula. The valueof a (i.e. the randomization fraction) in this case would be 27.5%. Thatis 55% would be initially randomized to placebo and 45% to activetreatment in the first phase. This could be accomplished by randomizingthe first block of study participants to the three treatment groups (DP,PP, PD) at ratios of 9:5:6, the second group at 9:6:5, repeating thispattern for the next 6 groups and randomizing the last group at ratiosof 3:3:5.

If 75% are randomized initially to placebo (with a 2:3:3 ratio ofDP:PD:PP in blocks of 8) and 25% to active treatment, the power is 87%based on the well-known asymptotic formula.

If a conventional technique having only one period and equalrandomization were used to design the study, the power would be 80%based upon the asymptotic formula. To achieve the same power value (i.e.the 90% power value achieved using the SPCD technique) it would benecessary to use 260 study participants (vs. the 172 study participantsused to achieve 90% power value using the SPCD technique).

The power was also calculated by simulation of 5,000 clinical trials.The simulation results were used to provide calculations; in that casethe corresponding power values were 94% and 87%.

If the estimates of the placebo response rate turn out to be overlyconservative, the 55% random allocation to placebo may yield too fewstudy participants to enter the second phase. For this reason, it may bepreferable to use the 75% random allocation to placebo as shown in FIG.3.

It should be noted that in the example of FIG. 3, the proportionsrandomized to the three groups are done so in a ratio 1-2a:a:a. Theresponse rates to the first administration of drug and placebo can bedenoted as p₁, q₁ respectively and the drug and placebo response ratesto the second treatment can be denoted as p₂, q₂ respectively.

In one embodiment, the data analysis involves computing a value hrepresentative of the effectiveness of the treatment. The effectivenessof the treatment, h, may be computed as:h=w(p ₁ −q ₁)(1−w)(p ₂ −q ₂)in which:w=a weighting factor

The weighting factor, w and the randomization fraction a are chosen tomaximize the power of the test, based on the alternative hypothesis.

Computation of the standard error for the effectiveness value h requiresconsideration of the fact that some of the same study participants whoare included in the estimation of p₂, q₂ are also included in theestimation of p₁, q₁. The delta method was used to compute the standarderror of the value of the effectiveness of the treatment h. Thecomputation is facilitated by considering the following table ofoutcomes, where in this case the response rates to the firstadministration of drug and placebo p₁, q₁ and the response rates to thesecond administration of drug and placebo P₂, q₂ are the theoreticalprobabilities (rather than the observed relative frequencies).

Group Response Frequency Probability 1-Placebo-Placebo No-Yes n_(1,1) (1− q₁) * q₂ No-No n_(1,2) (1 − q₁) * (1 − q₂) Yes n_(1,3) q₁2-Placebo-Drug No-Yes n_(2,1) (1 − q₁) * p₂ No-No n_(2,2) (1 − q₁) * (1− p₂) Yes n_(2,3) q₁ 3-Drug Yes n_(3,1) p₁ (this is the drug-placebo Non_(3,2) 1 − p₁ group, but the data from phase 2 on placebo are notconsidered in the analyses)

Then, the effectiveness value, h, may be computed as:

${h = {{w\left( {\frac{n_{3,1}}{n\left( {1 - {2a}} \right)} - \frac{\left( {n_{1,3} + n_{2,3}} \right)}{2{na}}} \right)} + {\left( {1 - w} \right)\left( {\frac{n_{2,1}}{n_{2,1} + n_{2,2}} - \frac{n_{1,1}}{n_{1,1} + n_{1,2}}} \right)}}},$

in which:

-   -   n is the total number of study participants;    -   n_(1,1) is the number of participants who were non-responders to        placebo in the first phase and were responders to placebo in the        second phase;    -   n_(1,2) is the number of participants who were non-responders to        placebo in the first phase and were non-responders to placebo in        the second phase;    -   n_(1,3) is the number of participants who were responders to        placebo in the first phase and were responders to placebo in the        second phase;    -   n_(2,1) is the number of participants who were non-responders to        placebo in the first phase and were responders to treatment in        the second phase;    -   n_(2,2) is the number of participants who were non-responders to        placebo in the first phase and were non-responders to treatment        in the second phase;    -   n_(2,3) is the number of participants who were responders to        placebo in the first phase and were responders to treatment in        the second phase;    -   n_(3,1) is the number of participants who were responders to        treatment in the first phase;    -   w is a weighting factor; and    -   a is a randomization fraction.

The standard error of h (denoted as h_(standard error)) can be computedas:h_(standard error)=√{square root over (D′VD)}

in which:

-   -   D is the column vector of derivatives of h with respect to        n_(3,1), n_(1,3), n_(2,3), n_(2,1), n_(2,2), n_(1,1), n_(1,2);    -   D′ is the transpose of D; and    -   V is the variance covariance matrix of n_(3,1), n_(1,3),        n_(2,3), n_(2,1), n_(2,2), n_(1,1), n_(1,2) from the multinomial        distribution.

It should be appreciated that the standard error of h,h_(standard error), is computed with the observed values of p₁, p₂, q₁,q₂.

The formula below is a simplified calculation of the standard error ofh.

$\sqrt{\frac{\begin{matrix}{{{- 2}\left( {{- 1} + {2a}} \right){p_{2}\left( {{- 1} + w} \right)}^{2}} + {2\left( {{- 1} + {2a}} \right){p_{2}^{2}\left( {{- 1} + w} \right)}^{2}} - {2\left( {{- 1} + {2a}} \right)}} \\{{q_{2}\left( {{- 1} + w} \right)}^{2} + {2\left( {{- 1} + {2a}} \right){q_{2}^{2}\left( {{- 1} + w} \right)}^{2}} + \left( {{- 1} + q_{1}} \right)} \\{\left( {{\left( {{- 1} + q_{1}} \right)q_{1}} + {2{a\left( {{- p_{1}} + p_{1}^{2} + q_{1} - q_{1}^{2}} \right)}}} \right)w^{2}}\end{matrix}}{2{a\left( {{- 1} + {2a}} \right)}{n\left( {{- 1} + q_{1}} \right)}}}$

To test the null hypothesis z=h/s was used. The values of a and w werecalculated by substituting the alternative hypothetical values of p₁,p₂, q₁, q₂ and finding the values of a and w that maximize z. The powerof the test is then Φ (z−1.96) where Φ is the cumulative distribution ofthe normal distribution.

FIG. 4 is a schematic representation of another example of the SPCDmethodology applied to a population with major depressive disorder(MDD).

Referring now to FIG. 4, a diagrammatic representation illustrates thephases and organization of a planned MDD treatment study arrived atusing the above-described clinical study design methodology.

As shown in FIG. 4, a group of selected study participants 110 b aredivided into three possible groupings as follows: (1) those who areexcluded from the study 120 b; (2) those who are eligible and who agreeto be randomized 122 b; and (3) those who are eligible but who declineto be randomized 124 b. The eligible study participants who agree to berandomized are randomized into three groups. This selection process isreferred to as the subject selection phase.

Next, in the first phase of the study, a first group 130 b receivesactive treatment. In this example, the eligible study participantsreceive an active treatment for six weeks. The particular length of timeof any study depends upon a variety of factors well known to those ofordinary skill in the medical field.

A second group 132 b receives placebo for the same duration of time asgroup 130 b which receives the active treatment (i.e. study participantsin group 132 b receive the placebo treatment for six weeks).

Similar to the second group, a third group 134 b also receives placebofor the same duration of time as the first group 130 b and the secondgroup 132 b.

Once the first phase of treatment ends, the study participants in eachof the groups 130 b, 132 b, 134 b are separated into responders andnon-responders. In group 130 b, those study participants who showimprovement are considered responders and those study participants whodo not show improvement are considered non-responders. Similarly, ingroups 132 b and 134 b, those study participants who show improvementare identified as responders while those study participants who do notshow improvement are identified as non-responders.

After the responders and non-responders are identified, the second phaseof the study begins. For the active treatment group 130 b, responders140 b enter open continuation therapy. Non-responders 142 b continue thestudy and receive placebo (or continue active treatment) for another sixweek phase.

The first placebo group responders 144 b also enter open continuationtherapy, while the first placebo group non-responders 146 b continue thestudy and receive active treatment for another six week phase.

The second placebo group responders 148 b enter open continuationtherapy, while the second placebo group non-responders 150 b continuethe study and receive placebo for another six week phase.

After the second phase is completed, the data from both phases of thestudy are pooled and analyzed to determine the effectiveness of thetreatment.

In summary, a method of performing a clinical drug trial with a reducedplacebo effect has been described. In its typical embodiment, the methodincludes randomizing study participants into three treatment groups andperforming a first phase of treatment testing on the three groups. Thefirst phase of testing comprises administering an active treatment to afirst group, and administering a placebo to a second group and to athird group. Responders and non-responders are determined for each groupat the end of the first phase. A second phase of testing is thenperformed. The second phase of testing comprises administering placebo(or continuing active treatment) to non-responders in the first group,administering active treatment(s) to non-responders in the second group,and administering placebo to non-responders in the third group. The datafrom the first phase of testing and from the second phase of testing(for the placebo non-responders during the first phase only) areanalyzed to provide the response rate to active treatment(s) and theresponse rate to placebo. Since study participants in the second phaseof testing have already failed placebo during the first phase, theirplacebo response is reduced.

Having described preferred embodiments of the invention it will nowbecome apparent to those of ordinary skill in the art that otherembodiments incorporating these concepts may be used. Accordingly, it issubmitted that the invention should not be limited to the describedembodiments but rather should be limited only by the spirit and scope ofthe appended claims.

1. A method of performing a clinical trial comprising: performing a first phase of testing comprising: randomizing participants into a first plurality of treatment groups including a first active treatment group, a first placebo group, and a second placebo group; administering the first active treatment group with an active treatment; administering the first and second placebo groups with a placebo; analyzing the participants for response; sorting the participants, based upon the analyzing the participants for response step, by creating at least a first non-responders to active treatment group, a first responders to active treatment group, a first non-responders to placebo group, a first responders to placebo group, a second non-responders to placebo group, and a second responders to placebo group; and creating a non-responder group comprising a combination of one or more members from the first non-responders to active treatment group, one or more members from the first non-responders to placebo group, and one or more members from the second non-responders to placebo group; performing a second phase of testing comprising: allocating one or more members of the non-responder group into a second active treatment group and a third placebo group; administering the second active treatment group with the active treatment; administering the third placebo group with the placebo; and analyzing the allocated one or more members of the non-responder group for response; and analyzing, using a processor, the efficacy of the active treatment by: analyzing response data of the first phase of testing based on a number of participants in the first responders to active treatment group, a number of participants in the first responders to placebo group, and a number of participants in the second responders to placebo group; analyzing response data of the second phase of testing based on a number of participants in the second active treatment group, determined based on said analyzing the allocated one or more members of the non-responder group for response step, and a number of participants in the third placebo group, also determined based on said analyzing the allocated one or more members of the non-responder group for response step; applying a first weighting factor to the response data of the first phase of testing; applying a second weighting factor to the response data of the second phase of testing; wherein the sum of the first weighting factor and second weighting factor equals a constant; and determining the efficacy of active treatment based on a combination of the result of the step of applying a first weighting factor to the response data of the first phase of testing and the result of the step of applying a second weighting factor to the response data of the second phase of testing.
 2. A method as in claim 1, wherein analyzing response data of the first phase of testing based on a number of participants in the first responders to active treatment group, a number of participants in the first responders to placebo group, and a number of participants in the second responders to placebo group, further comprises: analyzing a number of participants in the first non-responders to active treatment group, a number of participants in the first non-responders to placebo group, and a number of participants in the second non-responders to placebo group.
 3. A method as in claim 1, wherein the active treatment comprises one or more active treatments.
 4. A method as in claim 1, wherein the response of one or more members of the first non-responders to placebo group is included in analyzing the efficacy of the active treatment at least once in analyzing response data of the first phase of testing and at least once in analyzing response data of the second phase of testing, and the response of one or more members of the second non-responders to placebo group is included in analyzing the efficacy of the active treatment at least once in analyzing response data of the first phase of testing and at least once in analyzing response data of the second phase of testing.
 5. A method as in claim 1, wherein analyzing response data of the second phase of testing consists of analyzing response data for one or more members determined to be in the first non-responders to placebo group, and one or more members determined to be in the second non-responders to placebo group.
 6. A method as in claim 1, wherein, for each participant who is included in the analysis used in the determining of the efficacy of active treatment, the response results of such participant following the randomization of participants into a first plurality of treatment groups, and before any subsequent randomization of such participants, is utilized in the determining of the efficacy of active treatment.
 7. A method as in claim 1, wherein the first weighting factor differs from the second weighting factor.
 8. A method as in claim 1, wherein the active treatment or the placebo is administered to certain participants during the second phase of testing, but the response results of such participants during such second phase are not included in the analysis used in the determining the efficacy of active treatment.
 9. A method as in claim 1, wherein the active treatment is administered to certain participants during the second phase of testing only for blinding.
 10. A method as in claim 1, wherein members of the first responders to active treatment group who are participants in the second phase of testing are administered the active treatment.
 11. A method as in claim 1, wherein the determination as to whether a participant's response in the second phase of testing is utilized in the analyzing of the efficacy of the active treatment is based upon said participant's response in the first phase of testing.
 12. A method as in claim 1, wherein the active treatment comprises an active comparator. 